The overall objective of the proposed research is to understand how regulatory proteins interact with operons or chromosomes to control gene expression. This research is being pursued by several clearly defined approaches. (1) Regulation of transcription in the lac operon and bacteriophage lambda are being examined. The objective is to probe in precise biochemical and chemical terms how CAP functions to attenuate transcription, how the directionality and initiation site for E. coli RNA polymerase transcription is defined, and how cro protein, E. coli RNA polymerase, and cI repressor interact cooperatively and antagonistically on the same DNA. (2) Specific and defined studies, primarily on control protein-regulatory DNA, are designed to understand the individual elements of gene control. In particular, lac repressor-lac operator, lambda cI repressor-lambda operator, cro protein-lambda operator, and various restriction endonucleases are being examined in order to understand how proteins recognize and bind to specific DNA sequences.